Setanta does have quite a temper on him, but I find he does in fact generally know what he's talkiing about (at great length).
Good time travel story from the 50's, "Quit Zoomin' those Hands through the Air", by Jack Finney(as I remember it, not necessarily true in all details)
Old geezer's grandson is regaling him with stories of his dogfights in WWII. Granddad tells him to cut it out, the Civil War was still the big one, and he, the grandpa had done it all ninety years before.
He'd been wet behind the ears aide to a major who'd been a professor before the war and had invented something that was going to win the war, and they were on their way to get General Grant's blessing. Turned out the major had invented a time machine, and he figured that it was only a question of time til people invented powqered flight, so he was going to get a flying machine and win the war. He figured those first machines would be kept in the Smithsonian, so the major and the kid use the time machine to go to the Smithsonian at night, in 1950. They look thru the front door, and there's the Wright Flyer. They figure that's about their speed, so they go back to the 1860s again, walk a few feet til they'd be inside the Smithsonian, take the flyer down and back to the 1860s. the majort figures out it must run on something that will explode when fired, so they get the highest proof moonshine they can and fuel 'er up. The kid is small and light, the major is old and heavy, so the kid has to fly it. They fire it up, and the kid wobbles up and away, flies over the enemy lines and maps them so they'll know how to fight the big battle coming up. Then they return the Flyer to the Smithsonia, and go back home to the 1860s. Only thing was, the plane was unused to running on something so powerful, so it bucked and snorted and dipped and dived and veered, and the kid had sampled some of the fuel himself, and was schnockered, so he'd gotten turned around and mapped their own lines instead of the enemies, so they lost the battle and it was all for naught, and the flying machine was discredited, and nobody knew the true story of the firs airplane used in war. "So just quit zoomin' those hands thru the air, son", cause Graanddaddy did it before him and was really the first military aviator.